Recording drum with helical electrode

ABSTRACT

A recording drum with helical electrode wherein the electrode has legs which are joined to the surface of the drum by a body of elastomer material.

[451 Aug. 21, 1973 United States/Patent 91 Alden RECORDING DRUM WITHHELICAL [56] References Cited 'UNITED STATES PATENTS ELECTRODE 5/1971Alden 346/101 X FOREIGN PATENTS OR APPLICATIONS 2,729,818 l/1956 Bell et3,417,405 12/1968 Alden 3,577,150

m m m u mo fi h mm. GIM. mm w M mm MAB mu 0% mm mA MN 77 [rlul 221Filed: oa.4,1971 21] App1.No.:186,093

857,466 12/1960 GreatBritain..................

Primary Examiner-Joseph W. Hartary Attorney-Norman S, Blodgett RelatedU.S. Application Data [62] Division of Ser. No. 806,795, March 13, 1969,Pat.

346/139 C Gold 15/06 139 C, 139 R [52] U.S. [51] Int. Cl. 346/101 [58]Field of Search.............

PATENTED M1821 I973 u r M I MILTON ALDEN INVENTOR.

FIG. 5

RECORDING DRUM W ITII HELICAL ELECTRODE This is a division ofapplication Ser. No. 806,795 filed Mar. 13, 1969, now US. Pat. No. 3,61l,4.24.

BACKGROUND OF THE INVENTION In the art of recording by the passage ofanelectrical signal through a chemically treated paper,-it is wellknownto provide for horizontal sweeping or scanning by the use of a rotatinghelical electrode and a'straight blade electrode. Attempts to develop aninexpensive recorder for use in such a graphic communicationssystem havebeen frustrated by the fact that the operative elements'must be veryaccurately locatedrelativezto one another. This has meant that therecorder housing had to be manufactured and adjustedby highly-skilledpersonnel. Repair of the recorder because of-accidental dislocation ofthe critical elements has often required that the recorder be returnedto the factoryJFurthermore, the definition of the recorded image has"been less than of a desired qualitybecause ofratendencyof theelectrical signal to pass in paths :which are other than direct pathsbetween the electrodes. Th'esesa'nd other difficulties experienced withthe priorart devices have been obviated in a novel mannerby the presentinvention.

It is, therefore, an outstanding object of theinvention to provide arecording capsule which incorporateszall the important geometricrelationships of arecorder,

replaced in a recorder, thus avoiding repair'and adjustment by skilledpersonnel.

It is a further object of the invention toprovide arecording capsulewhich has means for shielding the gap between electrodes to produceimproved definition at low cost.

It is a still further object of the present invention to provide arecording capsule incorporating in a single replaceable elementlocatingsurfaces for a blade electrode of a recorder and a locating means forthe axisof a helical drum electrode.

SUMMARY OF THE INVENTION In general, the invention has to do with arecording capsule for use in a recorder. It includes a main plate havingan elongated slot and a drum rotatabiy mounted at one side of the platewith a helical electrode extending into the slot. Flexible teflonshields are mounted on locate the edge of a blade-type electrode whenthe capf sule is incorporated in'a ICCOI'dCIuThC plate 'is also providedwithbearing surfaces *accuratelyspaced relative to the locatingsurfaces; these bearing surfaces receive shaftsextending from the drum.

BRIEF DESCRIPTIONOF THE DRAWINGS The character of the invention,however,*may be best .understood 'by reference'to one of itszstructuralforms, as illustrated by the accompany-ing drawings, in=w hi'c":h:

FIG. '1 is a perspective'view of a"recording -ca'psu-le embodying theprinciples of the present invention,

-f-FIG. 2.is a sectional viewoffthe capsuletakenon the :line II,II of.FIG. 1,

FIG. 3 is :an .enlarged'view. of ithetoperativeportions to'f' thecapsule,

FIG.'4'isa view'taken on theline: IV- Wof FIG.3, "FlG..-5 is a sectionalview ofa portiono'f' theapparaatus, and

FIG.*6 is an end view of the-apparatus.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring first to FIG. 71,whichibest*showsthergeneral featuresof the invention, the recordingcapsule, indicated generally by the fefcrence :numeral 10, is

shownready for incorporation into agraphiccommuni- .-A drum '13 isrotatably'mountedaatone sideofthe plate :and is provided with a helicalelectrode 114 which ex- :tends into the slot; the drum is of=the typeshown and described in the patent application tot Alden, Ser. No.

793,132, filed Jan. 22, 1969 now US. Pat. No. 3,577,150.

Flexible shields 115 and :16 are mounted on "the other sideoftheslot.Theshields I5 and 31 6 :are gprovided'with straight spaced paralleledges 17 and 318, respectively, which lie adjacent the center'line-ofthe slot to define a narrow recording gap. The shields l5 and [6 areformed of teflon sheet, so that they present lit'tle 'friction to thehelical electrode 14 and .a straight blade electrode 19 (see FIG. 3) ofthe recorder. Furth'en the nature of such elastorneric plastics iis thatthey will not injure the tender surface of the moist, chemically treatedpaper. At the same time, the material wears very little.

As is best evident in FIG. 5, the helical electrode F11 consists of asheet metal strip which has laterally extending tabs 21 whose ends areembedded in mounds 22 of elastomer cement (such as a silicone plastic)on the surface of the drum.

The plate is provided at each end of the slot 12 with an integralabutment with a locating surface 23 which serves as a stop for the edgeof the blade electrode 19,

' which it will be understood is resiliently biased toward engagementwith the helical electrode.

A leg 24 extends from the underside of the plate at each end of theslot, so that one leg is provided under and corresponding to each of thelocating surfaces 23. Each leg has a cylindrical bearing surface 25 (seeFIG. 6) accurately located a predetermined distance from itscorresponding locating surface. The drum 13 has a shaft 26 which isaccurately located coai'rially of the operative edge of the helicalelectrode. The shaft is adapted to nest tightly against the bearingsurface 25 and the shaft shown in FIGS. 1 and 6 is formed with a thesurface of the shaft opposite that engaged by the bearing surface 25.

The drum 13 consists in the preferred embodiment of a cardboard tube 31in each end of which is inserted a plastic plug 32 in which the shaft 26is fixed.

In operation, the rotation of the drum 13 causes successive portions ofthe helical electrode to appear in the gap between the edges 17 and 18of the shields l operative edge of the helical electrode is adiamondshaped figure (see FIG. 4), the passage of current between thetwo is by ion migration from one to the other.

The paper is in a highly moist condition and the moisture is anelectrolyte; this means that the path of ion flow deviates in practicefrom a straight line. This results in a visual image whose definitioncan be less than perfect because of this stray migration. in the presentdevice, however, the shields l5 and 16 act as insulating members thattend to inhibit the sidewaysflow of current. The gap between the edges17 and 18 is only slightly larger than the width of the blade electrode19,

as is best evident in FIG. 4, and this has a tendency to l restrict thewidth of the recording path and toimprove the definition. Similarly, ifone wishes to increase the thickness of the two electrodes to increasetheirdura- 4 bility, this can be done without sacrificing the definitionof the recorded image.

The fact that the important geometric relationship v between the twoelectrodes is determined by surfaces entirely within the capsule meansthat the remainder of the recorder can be constructed without particularattention to accuracy and ability to adjust. The locating surfaces 23and the bearing surfaces 25 can be accurately related, for instance, bymolding the plate and legs as a one-piece precision plastic injectionmolding. if, during the operation of the recorder, the quality of theimageseems to be deteriorating, it is only necessary to remove thecapsule and replace it with a new one. There is no need to ship theentire recorder back to the factory for repair or adjustment. Duringmanufacture there is no need for final adjustments by skilled personnel;the recorder is assembled to joining'the capsule to the recorder proper.

With these and other objects in view, as will be apparent to thoseskilled in the art, the invention resides in the combination of partsset forth in the specification and covered by theclaims appendedhereto.

I claim:

1. A recording drum, comprising a main body having a cylindrical surfaceand having a helical electrode attached thereto, the electrodeconsisting of a strip'por= tion providing a helical edge and having aplurality of laterally extending legs, the free end-of each legextending into and held by a small body of elastomer plastic lyingon-tlie'said cylinder surface of the drum, the elasresiliently, but alsobeing self-cementing to the leg and I. the main body to act as the soleconnection between

1. A recording drum, comprising a main body having a cylindrical surfaceand having a helical electrode attached thereto, the electrodeconsisting of a strip portion providing a helical edge and having aplurality of laterally extending legs, the free end of each legextending into and held by a small body of elastomer plastic lying onthe said cylinder surface of the drum, the elastomer plastic not onlyserving to mount the electrode resiliently, but also beingself-cementing to the leg and the main body to act as the soleconnection between them.